Method for continuous production of sputter-coated glass products

ABSTRACT

A method and apparatus for the continuous production of sputtercoated glass products; such as glass sheets, or other substrates, involving supporting one or more substrates to be coated on a rigid support-platen, passing the platens and substrates horizontally through a series of successive chambers aligned with one another, including an entrance chamber, a coating chamber and a discharge chamber, sealing compartments at the opposite ends of the coating chamber, at the entry end of the entrance chamber and at the exit end of the discharge chamber for sealing said chambers from one another and from the atmosphere, conveyor means in said chambers for carrying the platens and substrates therethrough, and means responsive to movement of the platens through said chambers for automatically and in timed sequence initiating and controlling the complete cycle of operations of the apparatus, including the travel of the platens through the successive chambers, the opening and closing of the sealing compartments and the sputter-coating of one or more continuous films of a selected material or materials on the substrates as they pass through the coating chamber.

' United States Patent Carmichael et al.

[ METHOD FOR CONTINUOUS PRODUCTION OF SPUTTER-COATED GLASS PRODUCTS [75] Inventors: Donald C. Cannichael; Douglas L.

Chambers; Chong T. Wan, all of Columbus, Ohio [73] Assignee: Shatterproof Glass Corporation, Detroit, Mich.

[22] Filed: July 8, 1974 [21] Appl. No.: 486,492

Related US. Application Data [60] Division of Ser. No. 400,561, Sept. 25, 1973, Continuation-impart of Ser. No. 305,877, Nov. 13, I972, abandoned, which is a continuation of Ser. No. 70,143, Sept. 8, 1970, abandoned.

[52] US. Cl 204/192; 117/124 C, [IS/49.1 [51] Int. CL ..C23C 15/00; C03C 17/06; C23C 13/08 [58] Field of Search 204/192, 298; [IS/49.1, 118/495 [56] References Cited UNITED STATES PATENTS 3,294,670 12/1966 Charschan et a1. 204/298 3,326,177 6/1967 Taylor 118/491 3,341,442 9/1967 Kay 204/192 3,525,680 3/1970 Davidse 204/192 3,652,444 2/1972 Lester et al........... 204/298 OTHER PUBLICATIONS B. J. Williams, et a1., Practical Design Aspects of a Dec. 9, 1975 Continuous Vacuum RF Sputtering Machine, J. Vacuum Sci. & Tech, 7, 278-281, (1970).

Primary Examiner-John H. Mack Assistant Examiner-Aaron Weisstuch Attorney, Agent, or FirmWilliam E. Nobbe [57] ABSTRACT A method and apparatus for the continuous production of sputter-coated glass products; such as glass sheets, or other substrates, involving supporting one or more substrates to be coated on a rigid support-platen, passing the platens and substrates horizontally through a series of successive chambers aligned with one another, including an entrance chamber, a coating chamber and a discharge chamber, sealing compartments at the opposite ends of the coating chamber, at the entry end of the entrance chamber and at the exit end of the discharge chamber for sealing said chambets from one another and from the atmosphere, conveyor means in said chambers for carrying the platens and substrates therethrough, and means responsive to movement of the platens through said chambers for automatically and in timed sequence initiating and controlling the complete cycle of operations of the apparatus, including the travel of the platens through the successive chambers, the opening and closing of the sealing compartments and the sputter-coating of one or more continuous films of a selected material or materials on the substrates as they pass through the coating chamber.

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w 885 97.9 W R. Power-Source H DC. Power Source 459 81 $561 56o D.C.Po\veP 50mm H Ass 1 816 DC? 50 4%9 Owe! LI (Le b METHOD FOR CONTINUOUS PRODUCTION OF SPUTTER-COATED GLASS PRODUCTS REFERENCE TO RELATED APPLICATIONS This is a division of application Ser. No. 400,561, filed Sept. 25, 1973.

This application is a continuation-in-part of pending application Ser. No. 305,877, filed Nov. 13, 1972, now abandoned which was a continuation of application Ser. No. 70,143, filed Sept. 8, I970 (now abandoned).

BACKGROUND OF THE INVENTION This invention relates to sputter-coating of glass products (especially window panes) and more particularly to a method and apparatus for sputter-coating such products by a continuous process.

The architectural trend toward using more glass in commercial buildings has been enhanced by the availability of special coated and tinted glasses which not only serve an aesthetic purpose but are also functional. The most significant advantages of the special coated glasses are in the area of air conditioning. Since it generally costs from 3 to 6 times more to cool a building one degree than to heat it by the same amount (depending on the amount of glass used on the exterior of a building), the use of an exterior glass which will reduce the amount of solar radiation entering a building can provide substantial savings since less air conditioning equipment is required and its operation is less costly.

Over the past decade the market for colored and reflective glass in commercial construction has grown significantly. Basically two types of glass are in use tinted and coated. Tinted glass is made by adding selected metals such as iron, cobalt, and nickel to the molten glass during production. This method is time consuming and wasteful in that when a different color of glass is desired, a fouror five-day run of glass must be discarded while the change is made and the new batch stabilized. Also, large quantities of different colors and types of glass must be inventoried. In addition, although tinted glass does reduce glare, it also absorbs solar heat and the absorbed heat is re-radiated from both sides of the glass. Therefore, a greater amount of heat is allowed to enter the building than with coated glass.

Coated or reflective glass is produced by depositing a thin continuous film of a reflective substance such as a metal on at least one of the surfaces of a glass sheet to reflect solar radiation. Coated glass reflects solar radiation much more effectively than tinted glass and coated glass absorbs much less radiation and therefore less heat is reradiated into the building. The glass sheet is preferably installed with the thin film on the outside of the building to reflect the maximum radiation. However, a durable exterior coating which will not rub or wear off the glass sheet has not yet been perfected. Most companies sell coated glass only in double glazing (two panes separated by an air space) and laminated forms with the thin film protected by an overlying second sheet of glass. The second sheet prevents the film from being worn off or scratched during window washing or by airbom objects or other causes.

There are several processes available for depositing a thin film of reflective coating on a glass substrate. One process that is being used commercially is the vacuum evaporation process. In this process, the coating material source is heated in a vacuum environment to a te m perature at which the energy of the atoms of the source material gain sufficient thermal energy to evaporate from the source. The substrate to be coated is placed within the line of sight of the source and the evaporated vapor condenses on its surface. The source is essentially a point source and therefore the coating deposited on a flat substrate will have a thickness distribution dependent on distances from the source. In order to deposit coatings of uniform thickness on large glass windows, the distance between the source and the substrate must be several feet and multiple sources must be used.

Another process for depositing a thin-film coating is called sputtering or sputter-coating. The process of sputter-coating has been known for some time. This process involves ion bombarding a target of the coating material in low-pressu re gaseous glow discharge to cause atomic particles of coating material to be dislodged and deposited on the substrate to be coated. We have found that the sputter-coating technique as applied in the present invention produces a product having superior optical properties and improved adhesion. In addition, sputtering also has the advantage over thermal evaporation techniques in that the source (the target or cathode) is not a point or line source but a surface source. This is a particularly important advantage in the present application involving coating of largearea substrates. If a target surface in sputtering is made to be parallel to the substrate surface over all areas of the substrate (like a flat target placed parallel to a flat substrate), the coating thickness will be extremely uniform. Any edge effect in the thickness uniformity can be minimized by making the target dimensions 2 to 4 inches larger than the substrate dimensions. The distance between the target and the substrate surfaces can thus be as close as 2 inches and a relatively small vacuum chamber is required. Sputtering is a somewhat slower process than the thermal vacuum-evaporation process. but for the thin optical coatings of interest this process results in superior control of coating thickness and the rate is satisfactory for commercial production. Because the source (coating) material fonning the target will last for a long time, sputtering is adaptable to a semicontinuous or continuous manufacturing operation.

Sputtering has the following advantages over the vacuum evaporation techniques currently in use for production of coated window glass;

A smaller deposition chamber can be used. The vacuum evaporation technique uses one or more point sources which must scan the surface during deposition and with larger substrates the necessary spacing between the sources and the substrate correspondingly increases. The target used in sputtering may be placed much closer to the substrate since point sources are not involved. This reduces the size and expense of the coating equipment.

Sputterng appears to be more reliable and maintenance free as a production system.

Sputtering allows more versatility as the materials may be easily changed from batch to batch. Also a multiple-layer coating of several materials may be deposited during a single run simply by incorporating a sequence of targets in the system. An example of this is the coating of a siliceous material or aluminum oxide protective layer over the reflective film immediately after deposition of the reflective film.

In sputter-coating according to the prior art, the substrate to be coated is placed in an enclosure containing a cathode (target) of the material to be sputtered and an anode which is positively biased with respect to the cathode to establish a gaseous discharge (ion plasma) between the anode and cathode. The enclosure is then sealed and evacuated and later backfilled with a low partial-pressure atmosphere of an ionizable gas such as argon. During operation of the apparatus, the coating material is deposited on the surface of the substrate as a uniform continuous film. After deposition, the apparatus is shut down and the coated substrate is allowed to cool under vacuum. The enclosure is then brought back up to atmospheric pressure, the seal broken, and the coated substrate removed. The next substrate to be coated is then placed in the enclosure which is resealed and again evacuated to the required pressure for operation. This process is time consuming, inefficient, and is not adapted to mass production.

Several semi-continuous, batch-type processes have been developed to increase the capacity of presently used apparatus. The semi-continuous processes generally involve rotating or indexing substrate holders which are loaded on a batch basis. These processes require complicated control systems and still have only limited capacity.

SUMMARY OF THE INVENTION The present invention provides a process and apparatus for sputter-coating glass products on a continuous production basis. The invention involving placing one or more sheets of glass or other products, to be coated in a horizontally disposed position on the upper surface of a support-platen and continuously passing the platen and sheet or sheets carried thereby horizontally through a series of three successive low pressure regions or chambers. An inert gas is continuously admitted into the central or coating chamber to maintain an inert gas atmosphere in said chamber such that a continuous flow of gas away from the coating chamber is maintained. A continuous film of a selected coating material is sputter-coated on the upper surface of the sheet or sheets as they pass through the coating chamher.

The products to be coated may be heated prior to coating to promote outgassing at the product surface and minimize thermal stresses. Typically the surface of the products are ion bombarded prior to coating to clean the surface. A continuous layer of protective material such as siliceous glass may be radio-frequency sputter-coated over the continuous film as the products pass through the coating chamber.

The apparatus of the present invention includes a first or entrance chamber having entry and exit open ings, a second or coating chamber adjacent the entrance chamber and having entry and exit openings, the entry opening of the coating chamber being in communication with the exit opening in the entrance chamber, and a third or discharge chamber adjacent the coating chamber and having entry and exit openings, the entry opening of the discharge chamber being in communication with the exit opening of the coating chamber.

Located between the entry and exit ends of the coating chamber and the adjacent ends of the entrance and discharge chambers are sealing compartments containing valve means operable to place the coating chamber in vacuum-tight relation to the entrance and discharge chambers or for establishing communication therebetween. Sealing compartments are also located at the entry end of the entrance chamber and at the exit end of the discharge chamber and contain valve means for placing said chambers in vacuum-tight relation with respect to the atmosphere or for opening said chambers to the atmosphere.

The apparatus includes means for evacuating the chambers and for providing an inert gas atmosphere in at least the coating chamber. The sputter coating means are mounted in the coating chamber and conveyor means move the platens and sheets carried thereby to be coated through the successive chambers. Heating means and ion bombardment means and radiofrequency sputter-coating means may, and preferably are, provided in the coating chamber.

The advantages of the present invention include continuous operation, simple feed-through means for transfer of the products through the successive chambers, and less vacuum pumping is required, especially diffusion pumping (where required). The present invention also reduces contamination of the coating material as it is deposited onto the glass substrate since the continuous flow of gas away from the central region of the coating chamber prevents atmospheric dust and other contaminants from mixing into the coating during deposition.

A typical product produced using the method and apparatus of the present invention would be a sheet of glass with a smooth continuous surface on which a continuous metallic film is sputter-coated, preferably to a thickness of from 50 to 400 A. The products of primary concern as architectural glass, vehicle windows, and oven windows, although the process and apparatus may be used to sputtercoat other types of products. The substrates are preferably conventional silicate glass including window glass, plate glass, and float glass, although any of the conventional or special purpose glasses may be used. The process may also be used to sputter-coat other types of materials such as ceramics and plastic sheets and strips.

In the production of window glass, the continuous film is preferably sputter-coated to a thickness of from about 50 to about 400A. Films having a thickness less than about 50 A do not provide any significant reduction in solar radiation transmittance and those having a thickness greater than about 400 A will impair the transmission of visible light. A smooth continuous layer of transparent protective material may be deposited overlying the continuous film to protect the film from wear. The protective material is preferably a siliceous material such as silicon dioxide (including quartz), silicon monoxide, or any of the conventional or special purpose glasses such as Pyrex. The protective glass may be clear or it may be tinted to modify the color of the finished article. Any of the forms of aluminum oxide may also be used as the protective material. The protective layer is preferably from about 0.01 to about I micron in thickness. Layers less than 0.01 micron in thickness do not provide any significant protection for the film and those in excess of 1 micron are uneconomical and may involve problems where materials having coefficients of thermal expansion different from the substrate are employed.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a side elevation of the apparatus for continuously sputter-coating glass sheets or other substrates according to this invention;

FIG. 2 is a fragmentary perspective view of a glass or other substrate provided with a reflective coating layer and a layer of a protective material thereon;

FIG. 3 is a top view of the entrance chamber and the first portion of the coating chamber; 5

FIG. 4 is a top view of the rear portion of the coating chamber and the discharge chamber;

FIG. 5 is a side elevation of the entrance chamber and the first and second sealing compartments at the opposite ends thereof;

FIG. 6 is a longitudinal section through the coating chamber;

FIG. 7 is a side elevation of the discharge chamber and the third and fourth sealing compartments at opposite ends thereof; 1

FIG. 8 is a front view of the coating apparatus looking into the first sealing compartment;

FIG. 9 is a plan view of the first sealing compartment and a portion of the entrance chamber;

FIG. 10 is a vertical transverse section of the entrance chamber taken on line 1010 of FIG. 1;

FIG. 11 is a detail view of the drive end of each of the conveyors in the entrance, coating and discharge chambers;

FIG. 12 is a vertical, longitudinal sectional view of the sealing compartment at the entry end of the entrance chamber taken on line l212 of FIG. 3;

FIG. 13 is an enlarged detail view of the valve unit provided in each of the sealing components;

FIG. 14 is a detail view of the switches and control member employed with each of the valve units;

FIG. 15 is a vertical, longitudinal sectional view of the sealing compartment between the entrance and coating chambers, taken on line 1515 of FIG. 3;

FIG. 16 is an enlarged sectional view of the sealing compartment between the entrance and coating chambers and portions of said chambers;

FIG. 17 is a top view of the sealing compartments at the entry and exit ends of the coating chamber;

FIG. 18 is a vertical transverse sectional view of the coating chamber taken on line 1818 of FIG. 1;

FIG. 19 is a vertical transverse sectional view of the coating chamber taken on line 1919 of FIG. 6;

FIG. 20 is a vertical view, partly in section, of one of the sputtering cathodes taken on line 2020 of FIG. 18;

FIG. 21 is a top view of the sealing compartment at the exit end of the discharge chamber and a portion of said chamber;

FIG. 22 is a diagrammatic view of the hydraulic and electrical control systems associated with the entrance and coating chambers; and

FIG. 23 is a similar diagrammatic view of the systems associated with the coating and discharge chambers.

The coating apparatus of this invention comprises generally a unitary elongated tunnel-like structure which, as illustrated in FIG. 1, embodies an entrance chamber E, a coating chamber C and an exit or discharge chamber D in alignment with one another. The successive chambers E, C and D are isolated from one another and from the ambient atmosphere and are separated from one another by interposed sealing compartments V1, V2, V3 and V4.

With reference to FIG. 2, the letter F designates a fragmentary section of a support platen which supports the substrate 8 to be coated, said substrate preferably consisting of a sheet or sheets of glass or other siliceous material. The support platen preferably comprises a 6 rigid metal plate of aluminum of magnesium alloy A; to V2 inch thick. One or more layers L of a selected metal, such as nickel or a nickel alloy, is sputter-coated upon the upper surface of the substrate as the platen moves through the successive chambers E, C and D. If desired, a protective layer FL of a siliceous material such as Pyrex glass may be deposited upm the base coating by radio-frequency sputtering.

In accordance with the invention, and by means of suitably actuated controls to be more fully hereinafter described, a platen supported glass sheet or substrate to be coated is carried on a loading cart T (FIG. 5) and delivered to the entry end of the first sealing compartment V1 and moved therethrough onto a conveyor 10- 5 cated in the entrance chamber E. When the entire platen is located in the entrance chamber E, the sealing compartment V1 is closed to the atmosphere and, at this time, the sealing compartment V2 is also closed. The entrance chamber E is then pumped down to the desired vacuum then backfilled with an inert gas, preferably argon, to a desired pressure and, by means of communicating conduits between chambers E and C, the vacuum in said chamber E is equalized with that continuously maintained in the coating chamber C.

When this equalization has been attained, the sealing compartment V2 is opened and the substrate carried and guided forwardly therethrough into the coating chamber C where it is received on a conveyor. As the platen continues its forward movement through coating chamber C, there is sputter-coated upon the upper surface of the substrate one or more layers of the desired metal or metals. During coating of the substrate, the desired argon pressure is established in the discharge chamber D and this argon pressure is equalized with that in coating chamber C, at which time sealing compartment V3 is open and sealing compartment V4 remains closed. The platen P is advanced continuously through coating chamber C, and then passes through sealing compartment V3 into the discharge chamber D. After the entire platen P is on chamber D, the sealing compartment V3 is closed. The said chamber D is then vacuum broken to the atmosphere, the sealing compartment V4 opened and the coated substrate S and platen P removed from the apparatus.

However, while the se aling compartment V4 is open, the walls of the discharge chamber D are dried by a warm-air purge unit which is vented to the atmosphere through the sealing compartment V4. Likewise, after the sealing compartment V2 is closed, the entrance chamber E is vacuum broken, after which the compartment V1 is opened to the atmosphere.

FIRST SEALING COMPARTMENT The sealing compartment V1 (FIGS. 5, 8, 9 and 12) is formed by a body structure or housing supported on the floor F by pedestals 101 made up of a front ve rtically disposed transverse wall 102, an oppositely disposed vertical rear wall 103, and side walls 104 and 105. The housing 100 further includes a horizontal bottom wall 106 integrally jointed to the walls 102-105. The bottom wall 106 has a lower panel 107 spaced therebeneath to provide a hollow cham ber 108 through which a coolant is adapted to be circulated from an inlet pipe 109 to an outlet pipe 110. The top wall I 13 of housing 100 is formed by panels 114 and 115 angularly disposed with respect to one another. Thus, the panel 114 angles upwardly from the front wall 102 while the panel 115 slopes downwardly and is joined at its lower edge to the rear wall 103.

The front wall 102 is provided with a horizontal, elongated opening 117 through which the platen P and substrates S to be coated pass in entering the sealing compartment V1, while the rear wall 103 has a similar aligned opening 118 for passage of the platen from compartment V1 into the entrance chamber E.

Extending forwardly from the front wall 102 is a horizontal platform 120 secured to said wall by bolts 123. The platform 120 supports at least two roller devices 124 for supporting the platen P as it is being moved from the cart T into the sealing compartment V1 through opening 117 in said front wall (FIG. A limit switch 125, mounted on the platform 120, is actuated by the leading end of the platen and controls an electric circuit which prevents accidental closure of the compartment V1 until the trailing end of the platen P has been received within the entrance chamber E (FIG. 5).

A hood I-[ is secured to the front wall 102 above the platform 120, said hood being connected to an exhaust system to draw off the heated air that is introduced into the entrance chamber E by a warm air purge unit for the purpose of warming and drying the interior of said chamber to prevent moisture from condensing on the chamber walls.

The top panel 114 of housing 100 mounts a pair of transverse aligned hydraulic cylinders 127 and 128 that are substantially identical with one another (FIGS. 8 and 9). These cylinders are mounted on a base plate 130 secured to a frame 131 (FIG. 12) afiixed to the angularly disposed panel 114. Carried by the base plate 130 are tubular pedestals 133 and 134 for supporting the cylinders 127 and 128.

The lower end of the cylinder 127 is supplied with pressure and for exhaust through a pipe 138 while the cylinder 128 is equipped with a like pipe 139. The upper end of cylinder 127 is connected to pressure and- [or exhaust sources by a pipe 140, with the upper end of cylinder 128 having connected thereto a pipe 141 for the same purpose. A piston rod 143, having a piston 144 within the cylinder 127, projects outwardly therefrom to actuate a limit switch 145 located at the upper end of its movement and a limit switch 146 at the lower end of its movement by means of a control member 147 carried by said piston rod. The switches 145 and 146 are mounted on a bracket 148 affixed to the body of cylinder 127.

As best seen in FIGS. 8 and 9, the piston rod 150 having a piston contained in cylinder 128 is equipped at its outer end with a control member 152 to similarly actuate (FIG. 14) a limit switch 153 at the upper end of its movement and a limit switch 154 at the lower end of its movement, said switches 153 and 154 being mounted by a bracket 155 on the cylinder 128. As will also be seen in FIG. 9, the pipes 138 and 139 are supplied with hydraulic pressure through suitable valves from a common distributor pipe 157. The pipe 140, however, is independently supplied through a distributor pipe 158, while the pipe 141 is supplied through a distributor pipe 159.

In this connection, the piston rods 143 and 150 enter the sealing compartment V1 through the pedestals 133 and 134 respectively and similar glands 160; heat dissipating units 161 being provided at the inner ends of said glands. The piston rods 143 and 150 of the respective cylinders are connected at their inner ends by means of pins 165 to blocks 166 secured to the upper surface of a plate 167 which forms the top component of a valve member generally designated by the numeral 168, a plate 169 forming the lower component and spaced from the plate 167 by bars 170.

The plates 167 and 169 are secured together by a continuous weld 171 thereby forming a hermetically sealed chamber 172 within the valve member 168. The chamber 172 is supplied with a circulating coolant through pipes 173 and 1 74 to maintain the valve member 168 within a suitable temperature range and to prevent deterioration of an O-ring 175 located in a groove in the bottom surface of the plate 169. To facilitate connection of the valve member 168 to the pipes 173 and 174 and enable freedom of reciprocal movements of said valve member, flexible hoses 176 are employed between the fittings 177 in the plate 130 and the plate 167.

The sealing compartment V1 is closed when it is desired to preclude entry of outside air into the entrance chamber E by the application of hydraulic pressure to the upper ends of the cylinders 127 and 128 to actuate the pistons 144 and 151 to move the valve members 168 into surface-to-surface contact with a fixed angular valve seat 179 secured to a base plate 180 that is sealed about its perimeter to the side walls 104 and 105, the bottom wall 106 and the panel 115 of top wall 1 13. The valve plate 180 is provided with a recess in which the valve seat 179 is secured by screws; 183; the valve seat 179 having a groove in its lower face to receive an O- ring 184 which is forced by the screws 183 against the plate 180. The plate 180 is kept at the desired temperature by means of a U-shaped tubular element 185 fixed to the under surface of said plate and connected to a source of supply through pipes 186 and 187. A horizontally elongated opening 188 is formed in the panel 179 and is longitudinally aligned with the openings or passages 117 and 118 at the opposite ends of the sealing compartment V1. As viewed in FIG. 8, the pipes 186 and 187 project outwardly through the side walls 104 and 105 of said sealing compartment.

THE ENTRANCE CHAMBER The entrance chamber E (FIGS. 3, 5, 12, 15 and 16) embodies a horizontal, elongated housing designated in its entirety by the numeral 200 and comprising a bottom wall 201, a top wall 202, side walls 203 and 204 and vertically disposed frq t and rear walls 205 and 206 respectively. The top wall 202 consists of a horizontal perimeter flange 207 which provides an open area 208 that is hermetically sealed by a top plate 209. The front wall 205 is sealingly secured to a rear wall 103 of the sealing compartment V1 by bolts or the like 210. In FIG. 16, wherein the structural details are shown in enlarged scale, the rear wall 206 is secured to the front wall 302 of the sealing compartment V2 by bolts 211. The desired seal is effected by an O-ring 212 located in a peripheral groove formed in the opposed surfaces of either or both the front and rear walls 206 and 302. The front wall 205 of entrance chamber E is provided with an opening 213 registering with the opening 118 in the rear wall 103 of sealing compartment V1, while the rear wall 206 thereof has an opening 214 aligned with the opening 317 in the front wall 302 of the sealing compartment V2.

A conveyor system 215 is provided in the entrance chamber E for carrying the platens P and substrates S supported thereon from the roller devices 214 on receiving platform 120 through the sealing compartment V1 and said entrance chamber E. This conveyor includes a pair of transversely spaced, endless roller-type chains 215 and 217 (FIGS. 3, 9, l1 and 12). These chains are trained about idler sprockets 218 keyed to a shaft 219 journaled in bearings 220 at the entry end of entrance chamber E and at the exit end thereof around sprockets 222 keyed to a driven shaft 223 journaled in bearings 224 (FIG. 11). Between the pairs of sprockets 218 and 222, the upper flights of the chains 216 and 217 traverse similar tracks 225 to adequately support the platens and substrates.

The shaft 223 is projected outwardly through the side wall 204 of entrance chamber E throuh a suitable sealing gland 226 and connected to an electrically energized clutch 227 (FIG. 3) to operatively connect shaft 223 to the drive shaft 228 of a motor 230 provided with a brake 231 (FIG. 3). The motor 230 is variably controlled to vary the speed of the conveyor, as will be hereinafter described, by means of a resistance unit 232. Driving power to the motor 230 can be discontinued by the clutch 227 and the brake 231 automatically applied as the platen approaches the sealing compartment V2 in the event that the same is closed. As will be more fully hereinafter noted, the operation of the motor 230 is initiated and/or halted by the use of suitable switches responsive to the movement of the platen P.

In the operation of the apparatus, the conveyor 215 is halted when the platen and substrate to be coated has been carried to a point adjacent the exit end of the entrance chamber E. The sealing compartment V1 is then closed, (with the sealing compartment V2 being also closed at this time) and the chamber E pumped down to the desired vacuum. The entrance chamber E is then backfilled with an inert gas (preferably argon) until the pressure in said chamber is equalized with the pressure continually maintained in the coating chamber C. When this has been achieved, with the sealing compartment V3 being closed, the sealing compartment V2 is opened and the conveyor 215 started to move the platen and substrate onto the conveyor 415 within the coating chamber C; both conveyors 215 and 415 being operated at the same speed. In order to effectively control the sequence of operations of the apparatus, the entrance chamber E is provided adjacent its entry end with a limit switch 235 which is connected into the circuit of the switch 125 on the receiving platform 120. This arrangement prevents inadvertent closure of the sealing compartment V1 until the trailing end of the platen has been received in the entrance chamber E.

A limit switch 236 located adjacent the exit end of entrance chamber E is actuated by the leading end of the platen to initiate several important functions. Firstly, the switch 236 (FIG. 22) causes actuation of the resistance unit 232 to decrease the speed of the conveyor 215 from a relatively high speed of around 60 PPM to a stop by deenergizing the clutch 227 and energizing the brake 231. After the sealing compartment V2 has been opened, the resistance unit starts the conveyor 215 to move the platen onto the conveyor 415 in the coating chamber at its high speed.

Secondly, switch 236 controls the introduction of hydraulic pressure to the upper ends of the cylinders 127 and 128 (FIGS. 8 and 9) to close the sealing compartment V1; the pressure being terminated upon the closing of the switches 146 and 154 by the control mem bers 147 and 152 carried by the piston rods 143 and 150 respectively. This closing of the switches 146 and 154 also starts the pump down of the entrance chamber E, and activates a timer which will, at the end of the pump down period, stop the pumping and start the backfill cycle with an inert gas until a vacuum gauge (not shown) is satisfied. An equalizing conduit system is then opened between chambers E and C to bring the vacuous conditions into equilibrium with one another. After this has been accomplished, the sealing compartment V2 can be opened.

As illustrated in FIGS. 13 and 5, the entrance chamber E is connected to a central vacuum pumping system by conduit 245 through a valve 246 and also to a backfill unit (not shown) by conduit 249 through a valve 250 and further to a vacuum break unit by conduit 253 and valve 254 to a bafiling chamber 255 (FIG. 5) which is employed to reduce any air turbulence as the vacuum in the chamber E is relieved preparatory to opening of the sealing compartment V1. This, of course, occurs after the platen has been moved into the coating chamber C and the sealing compartment V2 is closed.

Thus, while the sealing compartment V1 is closed, the valve 246 is opened to connect the entrance chamber E to a vacuum pump through the conduit 245. Through a timing device, when the valve 246 is closed, the valve 250 is opened to the backfill unit to admit an inert gas, such as argon, into the entrance chamber E until a vacuum gauge indicates that the required pressure therein has been reached. The backfill unit operates to raise the pressure in the chamber E to equalize the pressure therein with that in coating chamber C. Communication between the chambers E and C to achieve equilibrium is made through a conduit 260 while the equalization valve 261 is open to a main conduit system 262, as will be more fully hereinafter explained.

The entrance chamber E is also connected, by conduit 265 through a valve 266, to a warm air blower system to dry the interior of chamber E. This system includes generally a blower unit, a heater and an air purge unit. Between the heater and air purge unit, the system is connected by means of a by-pass valve that is adapted to shunt the warm air into the atmosphere while the chamber E is closed and under vacuum.

SECOND SEALING COMPARTMENT With reference particularly to FIGS. 3, 5, 10, 15, 16 and 17, the sealing compartment V2 is formed by a housing 300, supported by pedestals 301 on the floor F. The housing has a front vertically disposed wall 302, a vertical rear wall 303 and side walls 304 and 305. The bottom 306 of the housing is provided with a chamber 308 through which a coolant is passed from the inlet pipe 309 to the outlet pipe 310 (FIG. 10) in the same manner as described with reference to sealing compartment Vl. Similarly, the top wall 313 consists of the angularly disposed panels 314 and 315. The front wall 302 is provided with an elongated horizontal opening 318 registering with the opening 214 of the entrance chamber E and through which the platen and substrate pass upon entering the sealing compartment V2. The rear wall 303 of sealing compartment V2 has an elongated horizontal opening 317 which is aligned with a similar opening in the front wall of the coating chamber C and through which the platen and substrate pass into the coating chamber.

Carried by the top panel 314 of housing 300 is a pair of transversely aligned sealing mechanisms 327 and 328 (FIG. 17) similar to sealing mechanisms 127 and 1 1 128. The sealing mechanisms 327 and 328 are mounted on a base plate 330 secured to a frame 331 on the top panel 314 by means of tubular pedestals 332 and 334 supporting hydraulically operated cylinders 327 and 328. The lower end of the cylinder 327 is supplied with pressure through a pipe 338 while the lower end of the cylinder 328 is supplied by a pipe 339 for the same purpose. The upper end of cylinder 327 is likewise connected to a pressure source through the pipe 340, with the upper end of cylinder 328 being connected to a pressure source by pipe 341.

The piston rod 343 of a piston in cylinder 327 projects outwardly to actuate a limit switch 345 at the upper limit of its movement and a limit switch 346 at the lower limit of its movement through a control member 347 carried by said piston rod. The switches 346 and 347 are mounted on a bracket 348 secured to the cylinder 327. The piston rod 350 of a piston in cylinder 328 likewise carries a control member 352 to similarly actuate a limit switch 353 at the upper limit of its movement and a limit switch 354 at the lower limit of its movement, said switches being mounted by a bracket 355 on the cylinder 328.

As shown in FIG. 17, the pipes 338 and 339 to cylinders 355 and 356 are supplied with pressure from a common distributor pipe 357. On the other hand, the pipe 340 to cylinder 327 is supplied from a pipe 358, while the pipe 341 to cylinder 328 is supplied through a pipe 359. The piston rods 343 and 350 enter the sealing compartment V2 through the pedestals 333 and 334 and glands 360; heat dissipating units 361 being provided at the inner ends of said glands. The piston rods 343 and 350 are connected at their inner ends by pins 365 to blocks 366 secured to a plate 367 which forms the top component of a valve member 368 having a chamber 372 therein. This chamber is supplied by pipes 373 and 374 with a cooling fluid to maintain the valve member within an acceptable range of temperature. To enable reciprocal movement of the valve member 368, flexible hoses 376 are connected between fittings 377 in the base plate 330 and the plate 367.

The sealing compartment V2 is closed when the sealing compartment V1 is open to the atmosphere and the sealing compartment V1 then closed during pumping down of the entrance chamber E. The sealing compartment V2 is closed upon application of hydraulic pressure to the upper ends of cylinders 327 and 328 to move the valve member 368 into contact with the fixed panel 379 which is formed in the same manner as the previously described panel 179 in sealing compartment V1. The plate 380 is kept at the desired temperature by means of a U-shaped tubular element 385 fixed to the under surface of said plate and connected to a source of coolant through pipes 386 and 387. A horizontal opening 388 is provided in the panel 379 and is horizontally aligned with the opening 317 in the frontwall 302 of sealing compartment V2 and the opening 318 in the rear wall 303 of the housing 300.

COATING CHAMBER With particular reference to FIGS. 1, 3, 4, 5, 6, 16, 18, 19 and 20, the coating chamber C embodies an elongated housing 400 which comprises a bottom wall 401, a top wall 402, side walls 403 and 404 and front and rear walls 405 and 406 respectively. The top wall 402 has an inwardly directed flange 407 to provide an open area 408 that is hermetically sealed by a top plate 409, which will be more fully hereinafter described.

The front wall 405 (FIG. 16) of housing 400 is sealingly secured to the rear wall of the sealing compartment V2 by bolts 410, with the seal being effected by an O ring 412. The front wall 405 is provided with an opening 413 which registers with the opening 318 in the rear wall 303 of sealing compartment V2, while the rear wall of the coating chamber C has an opening 414 (FlG. 17) aligned with an opening in the front wall of the sealing compartment V3.

A conveyor 415 is provided within the housing 400 for receiving and carrying the platen P and substrate S as they pass through the openings 318 and 413 from the sealing compartment V2. The conveyor 415 comprises a pair of transversely spaced, horizontal endless rollertype chains 416 and 417 (FIGS. 3, 4 and 18). At the entry end of the coating chamber C, the chains are trained about idler sprockets 418 (FIG. 15) keyed to a shaft 419 joumaled in bearings 420, while the opposite looped ends of the chains are trained about sprockets 422 keyed on a driven shaft 423, journaled in gearings 424. Between the sprockets 418 and 422, the upper flights of the chains traverse similar tracks 425 to support the platen. The driven shaft 423 projects outwardly through the side wall 404 of the housing and gland 426 and is joined by an electrically energized clutch 427 to the drive shaft 428 of a motor 430 equipped with a brake 43] (FIGS. 4 and 22). The motor 430 is variably controlled to reduce and/or increase the speed thereof by means of a resistance unit 432. Normally, the conveyer 415 is operated by the motor 430 at a relatively low speed such as, for example, around 8 FPM until the substrate has been completely coated. The resistance unit 432 then increases the speed of the conveyor to, for example, around 60 FPM until the platen P an coated substrate S is received on a conveyor in the exit or discharge chamber D. Thereafter, the resistance unit 432 again reduces the conveyor to its slow speed before timing out.

The sequence of conveyor operations and the progressively occurring phases of the coating operations are automatically controlled by electrically operated means responsive to movement of the platen P. Thus, the coating chamber C is provided adjacent its entry end with a limit switch 435 that is connected to the circuitry of the switch 236 in the rear end of the entrance chamber E. This ensures against inadvertent closure of the sealing compartment V2 until the trailing end of the platen has cleared the said compartment and been completely received within the chamber C. A limit switch 436, located in the rear end of chamber C, is adapted to coact with a switch in the entry end of the discharge chamber D, for a purpose to be later described.

Referring to FlGS. 6 and 18, the bottom wall 401 of housing 400 is formed in its central area with a plenum chamber 437 having a conduit 438 connected with the diffusion pump of the main vacuum system. Near the entry end of coating chamber C, a conduit 440 (FIG. 3) is attached to the side wall 403 and connects into the general conduit system 262 which provides communication between the coating chamber C and discharge chamber D. To this end, a second conduit 441 (FIG. 4) is provided adjacent the rear end of the chamber C and communication with the discharge chamber D is controlled by a valve 442. When the pressure in the entrance chamber E is to be brought into equilibrium with that in coating chamber C, the equalization valve 442 is closed and by valve 216 communication is established 

1. A METHOD FOR THE PRODUCTION OF SPUTTER-COATED GLASS SHEETS, WHICH COMPRISES: A. FREELY SUPPORTING A GLASS SHEET TO BE COATED IN A HORIZONTAL POSITION ON THE UPPER SUBSTANTIALLY CONTINUOUS SURFACE OF A SUPPORT PLATEN, B. FREELY SUPPORTING SAID PLATEN AND GLASS SHEET HORIZONTALLY UPON A CONVEYOR MEANS, C. CONVEYING THE PLATEN AND SHEET HORIZONTALLY INTO A COATING CHAMBER, D. MAINTAINING A PREDETERMINED PRESSURE IN SAID COATING CHAMBER, E. SPUTTER-COATING A CONTINUOUS FILM OF A SELECTED COATING MATERIAL ON THE UPPER SURFACE OF SAID SHEET WHEN SUPPORTED IN THE COATING CHAMBER, AND F. REMOVING THE PLATEN AND COATED SHEET FROM SAID CHAMBER.
 2. The method of claim 1 in which an inert gas is continuously introduced into the central region of said coating chamber and continuously withdrawn laterally therefrom adjacent the opposite ends thereof to remove gas that is leaked into said chamber and thereby maintain a constant pressure therein.
 3. The method of claim 1, in which the sputter-coating means comprises a plurality of cathodes connected to individual power sources, and in which the power level to each individual cathode is independently controlled by movement of the platen.
 4. A method for the production of sputter-coated glass sheets, (and the like), which comprises: a. freely supporting a glass sheet to be coated in a horizontal position on the upper substantially continuous surface of a support platen, b. freely supporting said platen and glass sheet horizontally upon a conveyor means, c. conveying the platen and sheet horizontally into and through a series of at least three successive chambers having communication with one another and in which the central chamber is a coating chamber, d. sealing the coating chamber from the adjacent chambers when the platen and sheet are received therein, e. maintaining a predetermined pressure in the coating chamber, f. continuously circulating an inert gas through the coating chamber to maintain an inert gas atmosphere therein, g. sputter-coating a continuous film of a selected coating material on the upper surface of said sheet as it is conveyed through the coating chamber, and h. establishing communication between the coating chamber and the adjacent chambers in response to movement of the platen and sheet prior to and during delivery of the platen and sheet into the coating chamber and the subsequent discharge thereof from said coating chamber while maintaining the pressure in said coating chamber.
 5. The method of claim 4 wherein, in response to movement of the platen, a pressure is established and maintained in the chambers adjacent the coating chamber equal to the pressure in the coating chamber prior to and during the transfer of the platen into said coating chamber and its discharge therefrom, and in which the pressure in the chambers adjacent the coating chamber is subsequently released while the pressure in said coating chamber is maintained.
 6. The method of claim 4, in which a desired pressure is created in the chambers adjacent the coating chamber, and then introducing an inert gas into the adjacent chambers to equalize the pressures therein with the pressure in the coating chamber prior to and during transfer of the platen and sheet into the coating chamber and its discharge therefrom by by-passing inert gas from the coating chamber into the adjacent chambers.
 7. The method of claim 4, including the steps of heating the glass sheet and then cleaning said sheet by means of a glow discharge cleaning electrode prior to sputter-coating, and in which the power level to the cleaning electrode is controlled by movement of the support platen to guard against over-heating of said electrode.
 8. A method for the production of sputter-coated glass sheets, which comprises: a. freely supporting a glass sheet to be coated in a horizontal position on the upper substantially continuous surface of a support platen, b. freely supporting said platen and glass sheet horizontally upon a conveyor means, c. conveying the platen and sheet horizontallY into and through a series of at least three chambers having communication with one another and including an entrance chamber, a coating chamber and a discharge chamber, d. sealing the coating chamber from the entrance and discharge chambers when the platen and sheet are received therein, e. maintaining a predetermined pressure in the coating chamber, f. sputter-coating a continuous film of a selected coating material on the upper surface of the sheet as it is conveyed through said coating chamber, and g. effecting in timed sequence in response to movement of the platen the sealing of the entrance chamber and discharge chamber to the ambient atmosphere and the creation of a pressure in said chambers equal to that in the coating chamber prior to establishing communication between said chambers and conveying the platen and sheet from the entrance chamber into the coating chamber and from the coating chamber into the discharge chamber.
 9. The method of claim 8, including the steps of introducing an inert gas into the coating chamber, pumping down the entrance chamber and discharge chamber to a desired vacuum, backfilling the entrance and discharge chambers with an inert gas until the pressures therein are substantially equal to the pressure in the coating chamber, and then bringing the pressures in said entrance, coating and discharge chambers into equilibrium by by-passing inert gas from the coating chamber into the entrance and discharge chambers.
 10. A method for the production of sputter-coated glass sheets, which comprises: a. freely supporting a glass sheet to be coated in a horizontal position on the upper substantially continuous surface of a support platen, b. freely supporting said platen and glass sheet horizontally upon a conveyor means, c. conveying the platen and sheet horizontally into and through a series of at least three chambers having communication with one another and including an entrance chamber, a coating chamber and discharge chamber, d. sealing the coating chamber from the entrance chamber and discharge chamber when the platen and sheet are received therein, e. maintaining a predetermined pressure in the coating chamber, f. continuously circulating an inert gas through the coating chamber to maintain an inert gas atmosphere therein, g. sputter-coating a continuous film of a selected coating material on the upper surface of the sheet as it is conveyed through said coating chamber, h. establishing communication between the coating chamber and the entrance and discharge chambers in response to movement of said platen prior to and during transfer of the platen and sheet from the entrance chamber into the coating chamber and from the coating chamber into the discharge chamber, i. sealing the entrance chamber and discharge chamber from the ambient atmosphere in response to movement of said platen prior to and during such transfer to maintain the pressure in the coating chamber, and j. in timed sequence and in response to movement of the platen re-establishing communication between the entrance and discharge chambers and the ambient atmosphere after the platen and sheet have been conveyed from the entrance chamber into the coating chamber and from the coating chamber into the discharge chamber.
 11. The method of claim 10, wherein the pressure in the entrance chamber and discharge chamber is equalized with the pressure in the coating chamber prior to and during transfer of the platen and sheet from the entrance chamber into the coating chamber and from the coating chamber into the discharge chamber, and wherein the pressure in the entrance chamber and discharge chamber is released after the platen is received in the coating chamber and subsequently discharged therefrom respectively in timed response to movement of said platen.
 12. The method of claim 10, in which an initial pressure is first established in the entrance and discharge chambers, and in which thE said chambers are then backfilled with an inert gas to equalize the pressure therein with the pressure in the coating chamber piror to and during the conveying of the platen and sheet from the entrance chamber into the coating chamber and from the coating chamber into the discharge chamber.
 13. A method for the production of sputter-coated glass sheets, which comprises: a. supporting a sheet to be coated in a horizontal position on the upper surface of a support platen, b. passing the platen and sheet horizontally through a series of at least three chambers having communication with one another and including an entrance chamber, a coating chamber and a discharge chamber, c. sealing the coating chamber from the entrance chamber and discharge chamber when the platen and sheet are received therein. d. maintaining the coating chamber at a constant pressure in the range of 2 to 6 X 10 2 torr, e. circulating an inert gas through the coating chamber to maintain an inert gas atmosphere therein, f. sputter-coating a continuous film of a selected coating material on the upper surface of the sheet as it is carried through said coating chamber, g. establishing communication between the coating chamber and the entrance and discharge chambers during transfer of the platen and sheet from the entrance chamber into the coating chamber, and h. sealing the entrance chamber and discharge chamber from the atmosphere during such transfer to maintain the pressure in the coating chamber, i. in which the sputter-coating means comprises a plurality of cathodes and in which the power level to each indicidual cathode is independently controlled by movement of the platen.
 14. A method for production of sputter-coating glass sheets, which comprises: a. freely supporting a glass sheet to be coated in a horizontal position on the upper substantially continuous surface of a support platen, b. freely supporting said platen and glass sheet horizontally upon a conveyor means, c. conveying the platen and sheet horizontally into, through and out of a series of at least three chambers having communication with one another and including an entrance chamber, a coating chamber and a discharge chamber, d. maintaining a predetermined pressure in the coating chamber, and e. sputter-coating a continuous film of a selected coating material on the upper surface of the sheet as it is conveyed through said coating chamber, and in which, in timed sequence, and in response to movement of said platen through successive chambers, the following process steps are initiated and controlled: i. sealing the coating chamber from the entrance chamber and discharge chamber during the sputter-coating of the glass sheet, ii. sealing the entrance chamber and discharge chamber to the ambient atmosphere when the platen and sheet are received therein, iii. establishing and maintaining a pressure in the entrance chamber and discharge chamber equal to the pressure in the coating chamber prior to and during transfer of the platen and sheet from the entrance chamber into the coating chamber and from the coating chamber into the discharge chamber, iv. establishing communication between the coating chamber and entrance and discharge chambers during conveying of the platen and sheet from the entrance chamber into the coating chamber and from the coating chamber into the discharge chamber, v. resealing the coating chamber from the entrance and discharge chambers respectively after the platen and sheet have been received in the coating chamber and subsequently moved from said coating chamber into the discharge chamber, and vi. opening the entrance chamber and discharge chamber to the ambient atmosphere after the coating chamber has been resealed. 